The present invention relates to methods and apparatus to detect the presence of a gas and in particular to methods and apparatus for the detection of the presence of a tracer gas in a leak testing environment.
In traditional leak testing apparatus either an interior region or an exterior region of a part under test is placed at a higher pressure than the other of the interior region or exterior region of the part under test. As such, if a leak is present in the part under test, the gas will flow from the higher-pressure side of the part under test to the lower pressure side of the part under test. One method to monitor this flow of gas and hence detect the presence of a leak is with a pressure decay apparatus which monitors the pressure of the higher-pressure side of the part under test. A decrease in pressure could be an indication of a leak. Another method uses a mass spectrometry based apparatus to test for the presence of a tracer gas on the lower pressure side of the part under test. The tracer gas having been introduced on the higher-pressure side of the part under test.
Such apparatus provide the operator of the apparatus with an indication of whether a part under test has a leak or at least whether the part under test has a leak that exceeds a predetermined threshold value. Typically, the customer specifies the threshold value and the operator sets the threshold value of the apparatus. If the operator of the leak testing apparatus receives an indication from the leak testing apparatus that the part under test contains an unacceptable leak, i.e. the leak exceeds the threshold value, the operator knows that the part under test is rejected and the operator places the part in a queue for further testing. However, the operator has no knowledge of the location of the leak or whether subsequently rejected parts are leaking from approximately the same location or a different location.
In order to determine the location of the leak further testing is traditionally required. Once the location of the leak is determined changes can be implemented to the manufacturing process to minimize the number of future rejected parts. The location of the leak is typically determined in one of two methods. First, for larger leaks the location of the leak is determined by pressurizing the rejected part and submerging the rejected part into a water bath. The location of the leak is determined based on the presence of air bubbles emanating from the leak site. Second, for smaller leaks the location of the leak can be determined by pressurizing the rejected part with a tracer gas and passing a tracer gas detector, such as a sniffer apparatus, over the potential leak areas of the rejected part. The tracer gas detector draws the gas proximate to a probe on the tracer gas detector apparatus, into the probe, and past a detector to detect the presence of tracer gas. One method of drawing the gas proximate to the probe is with a fan unit that draws gas into the probe and eventually past the detector. The leak site is then noted and potentially changes to the manufacturing process will be implemented.
The two stage process described above requires additional resources, delays the determination of the location of the leak for a given part under test and delays the determination of whether the location of the leak is repeatable from rejected part to rejected part. Further, the above two stage process is very operator dependent, in that the operator must visually recognize the leak, denote the leak location, and subject each rejected part to a consistent testing procedure. Additionally, results vary from operator to operator in the ability of each operator to recognize leaks and denote leak locations.
In addition, traditional apparatus often use mass spectrometry equipment to detect the presence of a leak due to the need to detect small quantities of the tracer gas. Such apparatus require that the gas located on the lower pressure side of the part under test be drawn to a sensing element to analyze the gas to detect the presence of the tracer gas.
As such, a need exists for a leak detection apparatus that provides an indication of the location of a leak in a part under test generally concurrently with the initial leak testing of the part. Additionally, a need exists for a leak detection apparatus that provides an indication of the location of a leak and an indication or measurement of the leak rate. Further, a need exists for a cost effective leak detection apparatus.
In one exemplary embodiment, the present invention includes a leak testing apparatus configured to detect the presence of a leak in a part under test. The leak testing apparatus of the present invention in one example is further configured to determine the location of the leak in the part under test. In another example the leak testing apparatus is further configured to determine both the location of the leak in the part under test and the leak rate of the corresponding leak.
In another exemplary embodiment, an apparatus for detecting the presence of at least one leak in a first region of a part under test and for localizing the location of the at least one leak, wherein a first side of the first region contains a tracer gas and is at a higher pressure than a second side of the first region such that the tracer gas will emanate through the at least one leak from the first side to the second side comprises a plurality of sensors positioned proximate to the first region, each sensor being configured to detect the presence of a tracer gas emanating from a leak and to provide a sensing signal; and a controller connected to the plurality of sensors. The controller configured to provide a leak detection signal in response to at least a first sensor of the plurality of sensors detecting the presence of the tracer gas, the leak detection signal including leak detection information representative of the location of the leak in the first region based on the sensing signals received from at least the first sensor and a second sensor of the plurality of sensors. In one example, the apparatus further comprises an indicator configured to provide a visual indication of the location of the leak. In one variation, the indicator includes a display configured to display a first representation of the part under test and a sensor icon positioned on the first representation, the sensor icon corresponding to a location of a first sensor which is proximate to the location of the leak. In another variation, the indicator includes a display configured to display a first representation of the part under test and a leak graphic positioned on the first representation, the position of the leak graphic corresponding to a location of a first sensor which is proximate to the location of the leak.
In one exemplary method, a method of monitoring a part under test to determine whether a first region contains a leak, the method comprises the steps of locating a plurality of sensors proximate to the first region, each of the plurality of sensors configured to detect the presence of a tracer gas emanating from the leak and to provide a sensing signal; monitoring each of the plurality of sensors to determine if the tracer gas is being detected by any of the plurality of sensors; and providing a leak detection signal in response to at least a first sensor of the plurality of sensors detecting the presence of the tracer gas, the leak detection signal including leak location information representative of the location of the leak in the first region based on the sensing signals received from at least the first sensor and a second sensor of the plurality of sensors. In one example, the method further comprises the step of providing a first indication of the location of the leak. In one variation, the first indication includes displaying on a display a first representation of a part under test and a sensor icon positioned on the first representation, the sensor icon corresponding to a location of a first sensor which is proximate to the location of the leak. In another variation, the first indication includes displaying on a display a first representation of a part under test and a leak graphic positioned on the first representation, the position of the leak graphic corresponding to a location of a first sensor which is proximate to the location of the leak.
In yet another exemplary embodiment a computer readable media for use in a leak testing application to determine which of a plurality of sensors is proximate to a leak in a part under test comprises a software portion configured to load a data file corresponding to the location of the plurality of sensors, to monitor the plurality of sensors to determine if any of the plurality of sensors has detected the presence of a leak, to determine the location of the leak if at least a first sensor of the plurality of the sensors detected the presence of the leak, and to provide a visual indication of the location of the leak if at least the first sensor of the plurality of the sensors detected the presence of the leak. In one example, the software portion is further configured to provide a first representation of the part under test and a first sensor representation of the at least first sensor positioned on at least the first representation of the part under test. In another example, the visual representation of the at least first sensor is a sensor icon. In yet another example, the software portion is further configured to determine the location of the leak by determining which sensor of the plurality of sensors detected the maximum concentration of a tracer gas emanating from the part under test. In still a further example, the software portion is further configured to determine the location of the leak by determining which sensor of the plurality of sensors first detected the presence of a tracer gas emanating from the part under test. In still yet a further example, the software portion is further configured to determine the leak rate of the leak in the part under test. In one variation, the software portion further configured to provide a leak graphic positioned on the first representation of the part under test at a location proximate to the location of the leak.
In a further exemplary embodiment, the present invention includes a sensor apparatus configured to detect the presence of a gas, such as helium or hydrogen. In one example the sensor apparatus includes a sensor controller and is a networkable sensor apparatus, such that the sensor apparatus is capable of sharing information with other devices across a network. In another example, the sensor apparatus is configured to detect the presence and concentration of a gas, such as helium or hydrogen. In yet another example, the sensor apparatus is configured to be incorporated into a component to detect the presence of a gas.
In yet a further exemplary embodiment, a sensor apparatus for detecting the presence of a leak in a part under test, the part under test being pressurized with a gas including a tracer gas comprises a housing; a sensor configured to detect the presence of the tracer gas and to generate a sensing signal; at least a first portion of the sensor being contained in the housing; and an I/O interface coupled to the housing, the I/O interface being configured to provide a first connection corresponding to an analog output and a second connection corresponding to a network output; and a sensor controller connected to the sensor and the I/O interface and configured to generate an output signal based on the sensing signal generated by the sensor, the sensor controller further configured to determine if a network is present across the second connection of the I/O interface and to generate a data packet for transmission over the network if the network is present, the sensor controller being contained in the housing;. In one example, the sensor includes a thermal conductivity transducer. In one variation, a portion of the thermal conductivity transducer is accessible from an exterior of the housing and is positioned proximate to the exterior of the housing. In another example, the sensor controller is configured to detect the presence of a first network and the presence of at least one additional network. In one variation, the sensor controller is configured to provide the analog output over the first connection when neither the first network nor the at least one additional network are present. In yet another example, the sensor apparatus is a stand-alone leak detection apparatus, the sensor apparatus further comprising a power supply positioned within the housing and coupled to at least the sensor controller and an indicator viewable from the exterior of the housing, the indicator being configured to provide an indication of the presence of the tracer gas.
In still a further exemplary embodiment, a gas sensor apparatus for detecting the presence of a gas comprises a housing including a first outer surface; a sensor configured to detect the presence of the gas and to generate a sensing signal, the sensor including a transducer portion, the transducer portion positioned proximate to the first outer surface of the housing such that the transducer portion is contactable by the gas; a sensor controller connected to the sensor and configured to generate an output signal based on the sensing signal generated by the sensor; and wherein at least a portion of the sensor and the sensor controller are contained within the housing. In one example, the gas sensor apparatus further comprises an I/O interface being coupled to the housing and configured to connect the sensor controller to at least one device remote from the gas sensor apparatus. In one variation, the output signal of the sensor controller is a scaled analog output signal representative of the amount of the gas detected by the sensor, the scaled analog output signal being made available to the at least one remote device through a first connection of the I/O interface. In another variation, the output signal of the sensor controller is a digital signal representative of the amount of the gas detected by the sensor, the digital signal being made available to the at least one remote device through a second connection of the I/O interface. In still another variation, the I/O interface further includes at least one transceiver configured to receive the digital signal from the sensor controller and to generate and transmit a data packet containing the digital signal. In another example, the gas sensor further comprises an indicator configured to provide a visible indication signal, the visible indication signal being representative of the presence of the gas and the visible indication signal being viewable from the exterior of the housing.
In still another exemplary embodiment, a sensor apparatus for use with a network comprises a housing; a sensor configured to detect the presence of a tracer gas and to generate a sensing signal, the sensor including a first sensing portion, the first sensing portion being positioned such that the first sensing portion is contactable by the tracer gas; a sensor controller connected to the sensor and configured to generate an output signal based on the sensing signal generated by the sensor; a network controller connected to the sensor controller and configured to generate a network data packet, the network data packet including information based on the output signal generated by the sensor controller; a network interface connected to the network controller and adapted to connect the sensor apparatus to the network; wherein the housing is configured to contain at least a first portion of the sensor, the sensor controller and the network controller. In one example, the sensor includes a thermal conductivity transducer. In still another example, the sensor apparatus further comprises an indicator coupled to the sensor controller, the indicator including a first indicator configured to provide status information related to the sensor apparatus and a second indicator configured to provide an indication of the presence of the tracer gas.
In a further embodiment, the sensors are metal halide sensors and the tracer gas is hydrogen.
Additional features of the present invention will become apparent to those skilled in the art upon consideration of the following detailed description of the preferred embodiment exemplifying the best mode of carrying out the invention as presently perceived.